Is it possible to grab the css properties of a character style, with extendscript?

I don't think I will be able to go down this route due to our infrastructure

Do you mean you are not allowed to use the exportFile() method?

This writes the CSS to the System’s temp folder and the getStyleCSS() function returns the CSS—you could also go to the desktop or document folder. The advantage of the temp folder is it’s hidden.

The document needs to have a character style named "MyStyle" change as needed:

var doc = app.documents.item(0);
var styleCSS = getStyleCSS("MyStyle")

alert(styleCSS)


/**
* Gets the emitted CSS for a character style 
* @ param the name of the style to get 
* @ return the CSS string 
* 
*/
function getStyleCSS(n){
    var f = new Folder(Folder.temp + "/getcss")
    f.create();
    //var f = new Folder(Folder.desktop)
    var cs = doc.characterStyles.itemByName(n)
    cs.emitCss = true;
    var tf = doc.textFrames.add({contents:"A"});
    tf.parentStory.appliedCharacterStyle = cs;  
    var exPath = f + "/" +  doc.name + ".html";
    var cssPath = f + "/" +  doc.name + "-web-resources/css/idGeneratedStyles.css";
    tf.exportFile(ExportFormat.HTML, File(exPath));
    var cssText = readFile(cssPath)
    tf.remove();
    var regx = new RegExp("span."+n+"[^\\]]+\\}")
    return cssText.match(regx)
}

/**
* Read a text file 
* @ param file path 
* @ return file’s text 
*/

function readFile(p) {
	var f = new File(p);
	f.open("r");  
	var x = f.read();  
	f.close();
	return x; //returns the text in the file sampletext.txt
}